On Thursday, the conservative HFC took their seventh official position: They will oppose any spending bill that doesn't defund Planned Parenthood.

"Given the appalling revelations surrounding Planned Parenthood, we cannot in good moral conscience vote to send taxpayer money to this organization while still fulfilling our duty to represent our constituents. We must therefore oppose any spending measure that contains funding for Planned Parenthood."

It's a significant statement from the conservative group. It takes a four-fifths majority for the Freedom Caucus to take an official position, meaning Republicans would probably need Democratic votes to pass a CR if HFC members make good on their pledge. (While the official position doesn't state whether members would vote against a rule for such legislation, HFC members have shown a willingness in the past to vote against those sorts of procedural motions as well.)

Emboldened after members pressured House GOP leadership into changing course on the Iran nuclear deal, the HFC is staking out a clear position on Planned Parenthood and the CR. The group is practically daring Speaker John A. Boehner and other GOP leaders to try putting forth a stopgap spending measure that funds Planned Parenthood.

Boehner has tried to avoid — or at least postpone as long as possible — any direct confrontation with the Freedom Caucus, but a top GOP aide, asked for comment Thursday, said the shut-down strategy doesn't work — and the conservatives know it.

“Two years ago, the very same group of members went down this path without a strategy to win and later publicly admitted they made a mistake. If they want people to follow them again, they have a responsibility now to clearly define their endgame," the aide said.

With at least 42 members, the House Freedom Caucus could cause some vote problems. Additionally, more members are joining almost every week. (Rep. Randy Weber, R-Texas, recently told CQ Roll Call that he would be joining the HFC.) On top of the Freedom Caucus, there are a number of lawmakers who have signed onto a letter circulated before the August recess by Rep. Mick Mulvaney, R-S.C., pledging to oppose any spending bill that funds Planned Parenthood.